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Re: [Qemu-devel] [PATCH 01/12] event_notifier: enable it to use pipes
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH 01/12] event_notifier: enable it to use pipes |
Date: |
Thu, 19 Jul 2012 13:58:17 -0500 |
User-agent: |
Notmuch/0.13.2+60~g7ecf77d (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
Paolo Bonzini <address@hidden> writes:
> This takes the eventfd emulation code from the main loop and adds it
> to EventNotifier. When the EventNotifier is used for the main loop too,
> we need this compatibility code.
>
> Without CONFIG_EVENTFD, event_notifier_get_fd is only usable for the
> "read" side of the notifier, for example to set a select() handler.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
> event_notifier.c | 83
> +++++++++++++++++++++++++++++++++++++++++++-----------
> event_notifier.h | 3 +-
> 2 files changed, 69 insertions(+), 17 deletions(-)
>
> diff --git a/event_notifier.c b/event_notifier.c
> index 2c207e1..dde2d32 100644
> --- a/event_notifier.c
> +++ b/event_notifier.c
> @@ -20,48 +20,99 @@
>
> void event_notifier_init_fd(EventNotifier *e, int fd)
> {
> - e->fd = fd;
> + e->rfd = fd;
> + e->wfd = fd;
> }
>
> int event_notifier_init(EventNotifier *e, int active)
> {
> + int fds[2];
> + int ret;
> +
> #ifdef CONFIG_EVENTFD
> - int fd = eventfd(!!active, EFD_NONBLOCK | EFD_CLOEXEC);
> - if (fd < 0)
> - return -errno;
> - e->fd = fd;
> - return 0;
> + ret = eventfd(0, O_NONBLOCK);
> #else
> - return -ENOSYS;
> + ret = -1;
> + errno = ENOSYS;
> #endif
> + if (ret >= 0) {
> + e->rfd = e->wfd = ret;
> + qemu_set_cloexec(ret);
This is kind of redundant with EFD_CLOEXEC, no?
> + } else {
> + if (errno != ENOSYS) {
> + return -errno;
> + }
> + if (qemu_pipe(fds) < 0) {
> + return -errno;
> + }
> + ret = fcntl_setfl(fds[0], O_NONBLOCK);
> + if (ret < 0) {
> + goto fail;
> + }
> + ret = fcntl_setfl(fds[1], O_NONBLOCK);
> + if (ret < 0) {
> + goto fail;
> + }
> + e->rfd = fds[0];
> + e->wfd = fds[1];
> + }
> + if (active)
> + event_notifier_set(e);
Missing a curly..
The rest looks good.
Regards,
Anthony Liguori
> + return 0;
> +
> +fail:
> + close(fds[0]);
> + close(fds[1]);
> + return ret;
> }
>
> void event_notifier_cleanup(EventNotifier *e)
> {
> - close(e->fd);
> + if (e->rfd != e->wfd) {
> + close(e->rfd);
> + }
> + close(e->wfd);
> }
>
> int event_notifier_get_fd(EventNotifier *e)
> {
> - return e->fd;
> + return e->rfd;
> }
>
> int event_notifier_set_handler(EventNotifier *e,
> EventNotifierHandler *handler)
> {
> - return qemu_set_fd_handler(e->fd, (IOHandler *)handler, NULL, e);
> + return qemu_set_fd_handler(e->rfd, (IOHandler *)handler, NULL, e);
> }
>
> int event_notifier_set(EventNotifier *e)
> {
> - uint64_t value = 1;
> - int r = write(e->fd, &value, sizeof(value));
> - return r == sizeof(value);
> + static const uint64_t value = 1;
> + ssize_t ret;
> +
> + do {
> + ret = write(e->wfd, &value, sizeof(value));
> + } while (ret < 0 && errno == EINTR);
> +
> + /* EAGAIN is fine, a read must be pending. */
> + if (ret < 0 && errno != EAGAIN) {
> + return -1;
> + }
> + return 0;
> }
>
> int event_notifier_test_and_clear(EventNotifier *e)
> {
> - uint64_t value;
> - int r = read(e->fd, &value, sizeof(value));
> - return r == sizeof(value);
> + int value;
> + ssize_t len;
> + char buffer[512];
> +
> + /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
> + value = 0;
> + do {
> + len = read(e->rfd, buffer, sizeof(buffer));
> + value |= (len > 0);
> + } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
> +
> + return value;
> }
> diff --git a/event_notifier.h b/event_notifier.h
> index f0ec2f2..f04d12d 100644
> --- a/event_notifier.h
> +++ b/event_notifier.h
> @@ -16,7 +16,8 @@
> #include "qemu-common.h"
>
> struct EventNotifier {
> - int fd;
> + int rfd;
> + int wfd;
> };
>
> typedef void EventNotifierHandler(EventNotifier *);
> --
> 1.7.10.4
- [Qemu-devel] [PATCH 00/12] Portable thread-pool/AIO, Win32 emulated AIO, Paolo Bonzini, 2012/07/16
- [Qemu-devel] [PATCH 01/12] event_notifier: enable it to use pipes, Paolo Bonzini, 2012/07/16
- Re: [Qemu-devel] [PATCH 01/12] event_notifier: enable it to use pipes,
Anthony Liguori <=
- [Qemu-devel] [PATCH 02/12] event_notifier: add Win32 implementation, Paolo Bonzini, 2012/07/16
- [Qemu-devel] [PATCH 04/12] aio: provide platform-independent API, Paolo Bonzini, 2012/07/16
- [Qemu-devel] [PATCH 03/12] main-loop: use event notifiers, Paolo Bonzini, 2012/07/16
- [Qemu-devel] [PATCH 05/12] aio: add Win32 implementation, Paolo Bonzini, 2012/07/16
- [Qemu-devel] [PATCH 06/12] linux-aio: use event notifiers, Paolo Bonzini, 2012/07/16
- [Qemu-devel] [PATCH 07/12] qemu-thread: add QemuSemaphore, Paolo Bonzini, 2012/07/16